1. Field of the Invention
The present invention pertains to a foam insert filled pad for use with a support system for a patient interface device, and, in particular to a forehead support system for a patient interface device for supplying a flow of gas to a patient. The invention further pertains to a gas delivery system that incorporates such a forehead support system using such a foam insert filled pad.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube in their esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation (NIV). It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, such as a bi-level pressure that varies with the patient's respiratory cycle or an auto-titrating pressure that varies with the monitored condition of the patient. Typical pressure support therapies are provided to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), chronic obstructive pulmonary disease (COPD), or congestive heart failure (CHF).
Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device, which is typically a nasal or nasal/oral mask, on the face of a patient to interface the ventilator or pressure support system with the airway of the patient so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient. It is known to maintain such masks on the face of a patient by a headgear having upper and lower straps, each having opposite ends threaded through connecting elements provided on the opposite sides and top of a mask.
Because such masks are typically worn for an extended period of time, it is important the headgear maintain the mask in a tight enough seal against a patient's face without discomfort. A problem arises in that in order for the mask to maintain a seal without any undue gas leaks around the periphery of the mask, the mask may be compressed against the patient's face and thus be uncomfortable to the patient.
It is known to provide forehead supports associated with patient interface devices to provide a support mechanism between the mask and the patient's forehead. Patient interface devices having forehead cushions, spacers, or supports are described in U.S. Pat. Nos. 4,907,584; 5,243,971; 5,517,986; 5,570,689; 6,119,693 and 6,357,441. The forehead supports prevent the mask from exerting too much force on a patient's face at one general location by dispersing the load over a larger area, provide greater control of the force on the patient at certain pressure points, such as at the bridge of the nose, and provide stability to the mask.
Although these conventional patient interface devices have advanced the art, the need still exists for a patient interface device that improves upon existing devices, for example, to maximize patient comfort while minimizing leak, during delivery of a positive airway pressure or flow of gas to the airway of the user. For example, many conventional patient interface devices tend to focus on minimizing the area of a patient's face to which strapping forces are applied. As such, a need exists for improved pad designs for use in such applications.